题解 | 牛牛学数列5

#include <iostream>
using namespace std;
int main() {
    int n, sum1 = 1, sum2 = 1;
    cin >> n;
    if(n == 1 or n == 2){
        cout << 1;
        return 0;
    }
    for(int i = 3; i <= n; i ++){
        if(i % 2 == 1) sum1 += sum2;
        else sum2 += sum1;
    }
    if(n % 2 == 1) cout << sum1;
    else cout << sum2;
}